1. Technical Field
The present invention relates to a technique for reading out an image from a document by converting the image into an electronic signal, and, in particular, to a technique for reading out the image from both sides of the document.
2. Related Art
Some conventional image reading apparatuses such as a digital copier or a scanner can concurrently read both front and rear sides of a document supplied by an automatic document feeder (ADF) by using respective reading units. The conventional image reading apparatus of this type has a defect in that malfunction of any of the reading unit results in suspension of the overall operation of the image reading apparatus; and the apparatus cannot be used until the malfunction is corrected.